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  Java Practices -> Avoid empty catch blocks
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<div class='page-title'>Avoid empty catch blocks</div>

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<br>Most contend that it's usually a very bad idea to have an empty catch
block.
<p>When the exception occurs, nothing happens, and the program fails for
unknown reasons.
<p><b>Example</b>
<p>The "tried our best" comments below are an example of what <i>not</i>
to do :
<br>
<PRE>

<span class='keyword'>import</span> java.io.*;
<span class='keyword'>import</span> java.util.*;

<span class='comment'>/** How NOT to implement a catch.  */</span>
<span class='keyword'>public</span> <span class='keyword'>final</span> <span class='keyword'>class</span> BadCatch {

  <span class='keyword'>public</span> <span class='keyword'>static</span> <span class='keyword'>void</span> main( String... arguments ) {
    List&lt;String&gt; quarks = Arrays.asList(
      <span class='literal'>"up"</span>, <span class='literal'>"down"</span>, <span class='literal'>"charm"</span>, <span class='literal'>"strange"</span>, <span class='literal'>"top"</span>, <span class='literal'>"bottom"</span>
    );   

    <span class='comment'>//serialize the List
</span>    <span class='keyword'>try</span> {
      ObjectOutputStream output =  <span class='keyword'>new</span> ObjectOutputStream(
        <span class='keyword'>new</span> FileOutputStream(<span class='literal'>"quarks.ser"</span>)
      );
      <span class='keyword'>try</span>{
        output.writeObject(quarks);
      }
      <span class='keyword'>finally</span>{
        <span class='comment'>//flush and close all streams
</span>        output.close();
      }
    }
    <span class='keyword'>catch</span>(IOException exception){
      <span class='comment'>//TRIED OUR BEST
</span>    }
  }
} 
</PRE>
<br>
In general, when a exception occurs, it can be thrown up to the caller, or 
it can be caught in a <tt>catch</tt> block. When catching an exception, some 
options include :
<ul>
<li>inform the user (strongly recommended)
<li>log the problem, using the <a href='TopicAction2316-2.html'>JDK logging</a> services, or similar tool
<li>send an email describing the problem to an administrator 
</ul>

<P>Deciding what exactly to do seems to depend on the nature of the problem. If there is an 
actual bug in the program - a defect that needs to be fixed - then one might do all three of the above. 
In this case, the end user should likely be shown a generic "Sorry, we goofed" message, not a stack 
trace. It is usually
considered bad form to display a stack trace to a non-technical end user, or if exposing a stack trace may 
be a security risk.

<P>If the exception does <em>not</em> represent a bug, then different behavior may be appropriate. For example, if a 
problem with user input is detected and an exception is thrown as a result, then merely informing the user 
of the problem might be all that is required. 

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<div class='topic-section'>See Also :</div>
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  <a href='TopicAction2316-2.html?Id=143'>Logging messages</a> <br>
 
  
  <a href='TopicAction56bf-2.html?Id=227'>Avoid basic style errors</a> <br>
 
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